The Cosmos top 10 space stories of 2015

Number 10:

The Universe is slowly fading away

281215 spaceroundup 10 — The Large Magellanic Cloud, an irregular satellite galaxy of the Milky Way. A survey of the Universe shows it is losing energy as galaxies drift further apart. – ALAN DYER / GETTY IMAGES

Astronomers peering out into the deepest corners of the Universe have found its expiration date, stamped into the light from distant galaxies. By analysing the brightness of that light, the astronomers discovered the Universe today is only half as energetic as it was two billion years ago. Read more

Number 9:

Cassini unveils the wintry world of Enceladus

281215 spaceroundup 9 — As NASA’s Cassini spacecraft enters the final phase of its mission to Saturn, in October 2015 it made one final flyby of Saturn’s icy moon Enceladus, capturing this stunning image of the moon’s north pole. – NASA / JPL-CALTECH / SPACE SCIENCE INSTITUTE

The last time NASA's Cassini spacecraft flew by Saturn's moon Enceladus its northern regions were shrouded in darkness during the depths of winter. Cassini has now returned and delivers previously unseen images of the moon's north pole in unprecedented detail, taken from just 1,839 kilometres above the surface. Read more

Number 8:

The black hole that has outgrown its galaxy

281215 spaceroundup 8 — An illustration of a feeding black hole. Most galaxies have a black hole at the centre, but one galaxy has been found with a voracious black hole, seven billion times the mass of the Sun. – UNIVERSAL HISTORY ARCHIVE / UIG VIA GETTY IMAGES

Most galaxies have a black hole at the centre. These ultra-dense objects have a gravity so strong that not even light can escape them. We know these black holes exist because they distort the orbits of nearby stars and gas. One galaxy has been found with a voracious black hole, seven billion times the mass of the Sun. So why is this black hole the exception to the rule? Read more

Number 7:

Space junk: Catastrophe on the horizon

281215 spaceroundup 7 — An artist’s impression of how the near-Earth orbit is becoming a junk-yard, potentially threatening future space missions. – PETROVICH9 / GETTY IMAGES

They call it the Kessler syndrome. In 1978, NASA scientist Donald Kessler foresaw that if we continued to launch satellites and leave their paraphernalia floating in orbit, collisions would be inevitable. Each could produce a debris shower capable of crippling other satellites in a chain reaction that could spell the end of the satellite age. Satellite collisions have already begun. Can we clean up Earth's orbit and put a stop to this slow motion chain reaction before it's too late? Read more

Number 6:

The habitable zone

281215 spaceroundup 6 — If life requires liquid water then Europa would be the perfect place to look. The biggest sea in the solar system might lie beneath the scarred surface of Jupiter’s large frozen moon. It may carry more than twice the volume of liquid water found on Earth. – NASA / JPL-CALTECH / SETI INSTITUTE

Earth is teeming with life in the least likely places – in rocks kilometres below the ground, in acid or radioactive ponds, in volcanic springs under the sea and in lakes beneath the Antarctic. The tenacity of life in such ‘unearthly’ environments has led scientists to believe that maybe we’ll also find life elsewhere in the Solar System, such as on Jupiter's moon, Europa, above. Mars is generally considered the most likely candidate. Here are some other possibilities. Read more

Number 5:

What on Ceres are those bright spots?

281215 spaceroundup 5 — The color blue on Ceres is generally associated with bright material, found in more than 130 locations, and seems to be consistent with salts, such as sulfates. It is likely that silicate materials are also present. – NASA / JPL-Caltech / UCLA / MPS / DLR / IDA

If the aim of travel is to view strange new sights and broaden the mind, NASA’s voyage to the asteroid belt to examine Ceres and Vesta has been well worth the trip. As Ceres’s dull, frozen surface came into view of the Dawn space probe’s cameras earlier this year, mysterious bright spots could be seen glinting from the surface. What might have caused them has kept the world guessing. Read more NEED TO UPDATE THIS LINK

Number 4:

Looking for life in salty Martian streams

281215 spaceroundup 4 — Dark, narrow, finger-like streaks, visible against the white background of the lower slopes in this image, are believed to be marks made by flowing water. – NASA / JPL / UNIVERSITY OF ARIZONA

In 1895 Percival Lowell pointed his telescope at Mars and saw canals. Ever since, Earthlings have debated whether the Red Planet has running water. With great fanfare, NASA has concluded it does. And where there’s water, there may be life. But what form might it take and where should we would look? Astrobiologists are using clues from Earth’s cold deserts to find out. Read more

Number 3:

Watching a baby planet's birth

281215 spaceroundup 3a — Observations from the Large Binocular Telescope show a ring of dust and gas (grey), within which three newly formed planets (the flashes of colour) could be seen. – STEPH SALLUM

The first glimpse of a new baby is a happy event. Just ask the astronomers who spotted a Jupiter-like baby planet – the youngest planet ever directly observed through a telescope. Read more

Number 2:

Found: the first stars in creation

281215 spaceroundup 2 — An artist’s impression of CR7, a very distant galaxy three times brighter than any other known galaxy from this period. – ESO / M. KORNMESSER

The Universe began with a brilliant flash but soon descended into darkness – until finally, a few hundred million years after the Big Bang, the first stars flickered into life. Astronomers believe they have now glimpsed some survivors from this pioneering generation of stars. These ancient ancestors of modern stars were monsters, hundreds of times more massive than our Sun and millions of times as luminous. Their short, intense lives ended in giant supernova explosions that enriched the cosmos with the first heavy elements. Read more

Number 1:

Seeing Pluto for the first time

281215 spaceroundup 1 — Images of Pluto taken by New Horizons have awakened affection for the distant body. But should sentiment determine whether it is a planet? – NASA / JOHNS HOPKINS UNIVERSITY APPLIED PHYSICS LABORATORY / SOUTHWEST RESEARCH INSTITUTE

At the start of 2015, Pluto was one of the most mysterious objects in the Solar System, so remote scientists weren’t even sure of its size. Today – thanks to NASA’s New Horizons space probe – we not only have a clear measure of its diameter (2,370 kilometres, give or take 20 kilometres), but we know it has a red–streaked polar cap, steep mountains nearly as tall as New Zealand’s Mt. Cook, and a surface so fresh and smooth that scientists think it might still be geologically alive. And it looks like the cold distant body will continue to surprise us. See the full list of 2015 Cosmos stories covering Pluto here

Originally published by Cosmos as The Cosmos top 10 space stories of 2015

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